But even people who have solid genes, maintain a healthy weight and exercise in
moderation can feel the pain of worn knees, sore hips and wobbly ankles.

How did we get here? When we made the move to walk upright, didn’t our joints
evolve to carry the weight?

It turns out that there were trade-offs, said Amanda Agnew, an
evolutionary-anatomy specialist at Ohio State University.

“Our joints are not perfectly adapted to (our) posture,” she said. “Our spines,
hips, and knees are especially weak because of all the forces from gravity, weight,
moving around etc.”

Agnew said humans have a low center of gravity — between the knees and feet —
that requires some bones to grow at an angle and can create “weak spots” in or near the joints. Our
ancestors that walked on four legs had a higher center of gravity, located in the trunk, she said.
That meant fewer weak spots.

But to know the hips, knees and ankles, we need to understand the mechanics of
the modern human joint, which unites rigid bone and flexible ligament.

Joints are formed by the ends of two or more bones and are connected by thick
tissue. The ends of the bones are covered with a smooth layer of cartilage, which is supposed to
provide nearly frictionless movement.

But when the ligaments are stretched too far or damaged, stability is affected.
And when cartilage is damaged or diseased by arthritis, joints can become stiff and painful.

There are three kinds of arthritis: l Post-traumatic arthritis, which results
from injuries that don’t heal properly. l Rheumatoid arthritis, an autoimmune disease that attacks
joints, minimizing mobility and sometimes causing excruciating pain. It affects an estimated 2.1
million people in the United States. l Osteoarthritis, which is caused by wear on the joints and is
the most-common form of arthritis. It affects about 27 million Americans, most of them elderly.

Serious injuries — torn ligaments, broken bones and surgeries and a
family history of joint problems can lead to arthritis at younger ages, said Dr. Thomas Kovack, an
orthopedic surgeon at Doctors Hospital.

“We used to see 60-, 70-or 80-year-olds,” Kovack said. “Now it’s not uncommon to
see a 40-year-old.”

An MRI 10 years ago showed that Ann Heilbrunn had arthritis in her
left hip.She had a family history of arthritis, and at the time, she weighed about 300
pounds, adding stress to her joints.

“I lost the weight, but my hip got progressively worse,” said Heilbrunn, now 45,
who works at the nonprofit Center of Vocational Alternatives.

“I was basically walking on a broken hip,” she said.

Heilbrunn had the hip replaced in December. Now,she has no pain and
is able to be much more active. Doctors are monitoring arthritis in her right hip.

Orthopedic experts say there are a lot of treatment options for patients
experiencing the various stages of joint deterioration. Surgical joint replacements use metals or
ceramics as a substitute for worn bone and plastic for cartilage that has deteriorated.

Kovack said small pieces of cartilage can be removed and inserted in worn areas.
Cadaver cartilage is another option.

Doctors also can remove a small sample of cartilage from a patient, grow it
outside the body in a lab and reinsert it where needed.

Other treatment options for less-severe arthritis include rest, physical therapy
and medication.

But it might also be possible to stave off joint deterioration, at least
temporarily. Kovack said many joint problems can be kept at bay through common sense and
moderation.

“If it hurts, don’t do it,” he said.

Particular motions, such as squatting or kneeling, can increase joint pain for
some people and should be avoided when possible. msomerson@dispatch.com